Yeah, this idea of a narrative approach is a real brainteaser, I had a lot of trouble wrapping my head around it, too.
Now, it even bleeds over into other systems.
Which doesn't mean I have the eternal truth and all the answers, this is not supposed to be an "And thy lord sayeth thou shall play like this!" sort of thing, I just feel that people tend to over complicate things, me included.
One of the big question with Fate, and that goes double for Core: "What happens, when the roll fails?"
So here you are, prepared to start this great scene, where the wizard is going to chase down the bad guy with a spell...
...and the setup roll fails and you don't do the spell. Which reduces the overall coolness of the game, because you've just robbed yourself of this cool spell casting scene. Or you go ahead and do it anyway, but then what was that roll for?
For example, a player of mine wanted to create a pre-cast spell for a rescue mission. He wanted to have plants grow out of a prepared flower bed in a box, where he would sit in a circle in the middle. He wanted to have that thing pushed out of a truck into the building they needed to go in and catch all the bad guys with a 10 shift block in the relatively big cargo hall. He ended up having to gather 7 aspects to be able to fuel the spell, and that's where we left the last session. I went along with the block idea, because at the time, I felt it was the best thing to do.
But then I had a far better idea: I'll put those 7 aspects into use as 7 temporary fate points to buy powers and build a "plant creature", that the wizard can "turn" into like a were-creature. He then sits in the middle of this flower bed and goes through the scene fully controlling that bota-warrior. The alternative would have been him sitting there and concentrating on the spell, while the rest of the gang is off doing their stuff. Which is incredibly boring. Sure, he could have caught 50 bad guys easily with that version of the spell, but I can just as easily only put 5 guys in that scene and have him actively fight them. Way more action ergo way more fun.
Let's see what we can do with the things you mention.
Wards:Mostly, this can be seen as an aspect on things. "Warded" on your apartment, for example. Then there are a number of ways you could go. The bad guys are coming after you, but you don't want to fight them, you could spend a fate point on you apartments "Warded" aspect and say "you know what, my character is beat up and tired, he needs rest. Let's say the wards keep them out, and we'll deal with things in the morning."
If you want to make it more interesting, for example in a conflict, you can make it a character at the power level of the wizard that cast it. So a wizard with his magic skill at good (+3) would get a ward character that has a skill pyramid up to good as well. Give it a stunt that allows it to take an attack instead of another character, as long as he is behind it, and you're done.
Or treat it as a contest. Harry vs. the zombies comes to mind. Harry's magic roll vs. Grevaine's magic roll. In this case, I think Harry even took a concession here, when they tried to make a run for it.
Veil:Straight up "Create Advantage". The Aspect you create allows you to roll your magic skill for defense, just like you would with a shield, since it is just another type of shield, really. And it might grant you other opportunities, like being able to ambush someone.
Attack (or other lasting effects):Make it a conflict, or a contest, depending on your taste. It's just not all that interesting to go *roll* "You're dead." This goes for pretty much every lasting effect. If you win the conflict or contest, the effect takes place, if not, you got a mean headache and the target got away. If you want to bring in weaponry, you can create advantages before you cast the spell, so that a specifically potent symbolic link could be a weapon:2 in that conflict. Too high a bonus, and you won't even have to roll (like your +6 bonus, that's 3 aspects on every roll for free).
Conjuring:Usually, you don't conjure something just for the fun of it, it is part of solving a problem. So you just solve that problem with magic, with the usual rules, maybe a contest, maybe just an overcome action, and you describe it as conjuring something to help you. Grevaine, for example would roll an overcome action with magic to open a door and describe it as one of his zombies ripping it out of its hinges. Harry would describe it as blasting it open with sheer Forzare. A pyromancer might conjure up a magmaworm that crawls all over it and burns a hole into it. But they'd all face the same roll.
So, wall of text, I apologize, but I hope with the examples, you get what I am trying to say. Maybe it'll help you get more into the fate core spirit.